Generic diffusers, especially downstream of a compressor of a turbine, are well known from the prior art. The aerodynamic properties of these diffusers are influenced essentially by the contours of the inner and outer shell of the diffuser and by air guiding plates at a diffuser outlet, but also in particular by the guide vane row of the last compressor stage of an upstream compressor.
An essentially radial flow direction of the air mass flow induces, among other things, a secondary flow with a flow component in the radial direction, which can lead to critical blocking of the air mass flow within the diffuser and thus also to increased flow losses with regard to the air mass flow. Partial flow separations can also arise, which can lead to a severe reduction in the deceleration of the air mass flow at the diffuser, and accordingly also to a reduced static pressure at the diffuser outlet.
It is also known, from EP 0 628 728 A1, to arrange a so-called split diffuser between the compressor and an annular combustion chamber of a gas turbine, in order to supply the compressed air to a combustion chamber plenum with low losses. In that context, the split diffuser contains, on the outlet side, swirl-reduction vanes with identical outflow profiles, such that individual air streams leave with the same swirl. According to EP 0 651 207 A1, the segmentation of the outflow in the circumferential direction can also be brought about by means of individual rectangular ducts whose respective outlet openings are at different radii. According to FR 1 037 610, it is also possible for swirl-reduction vanes to be provided on the diffuser inlet side.
Overall, however, diffusers of this type are suitable only for use in a gas turbine with silo combustion chambers.
Furthermore, US 2007/0271923 A1 discloses a gas turbine in which guide elements are provided in order to reduce the flow losses between the diffuser outlet and the combustion chamber inlet. However, these appear to be attached in a manner which is both complex and associated with aerodynamic losses.